This invention relates to a portable upblast cleaning device. More particularly, it relates to a device of the type which utilizes one or more airless centrifugal blasting wheels for throwing particulate such as steel shot, grit or other abrasives against a surface. In particular, the present invention relates to a class of cleaning devices which are adapted for cleaning the underside of a horizontally disposed surface as, for example, the outside hull of a large ship. The device utilizes one or more airless centrifugal blasting wheels for throwing abrasive in an upwardly direction against the horizontally disposed surface. Sealing engagement with the surface is maintained by a flexible seal disposed around the blast area. The seal is maintained in contact with the blast area by various movable frame arrangements which are known in the art. After striking the surface, it is desirable to reclaim and reuse the abrasive.
In previous blast heads of the type described, there was a particular problem in recycling the abrasive due to the contamination and buildup of foreign particles in the device. As the buildup occurs, these particles mix with the abrasive and get recycled through the blasting device reducing its effectiveness and tending to clog or otherwise impair the efficiency of the device.
Another problem commonly experienced in devices of this class is the heat buildup about the blasting area due to the dissipation of kinetic energy of the particulate against the surface being treated. This heat buildup aggravates the contamination problem causing binding of refuse of abrasive. One way to solve the problem of contaminant buildup is to pass the abrasive through a separator as, for example, an air wash separator to remove the contaminant. Previous attempts have utilized a separator which is located at a remote point from the cleaning head. Accordingly, the abrasive must be transported by a conveyer system from the blast head to the remote separator and back again before reuse. This arrangement is not entirely satisfactory and tends to limit the portability and versatility of the unit.
It is accordingly an object of the present invention to provide an abrasive cleaning device which recycles spent abrasive for reuse.
It is another object of the present invention to provide a portable blast head which prevents buildup of foreign matter in the returned abrasive to prevent gumming and sticking of the apparatus.
It is another object of the present invention to provide an air flow in the blast area of the device to maintain the temperature in the blast area at a selected level.
It is a further object of the present invention to provide a portable blast head having an air flow in the blast chamber to enhance the conveying of abrasive towards the recycling section.
It is another object of the present invention to provide a device which permits rapid access to the blast wheel and impellor so that jams and buildup of foreign matter can be quickly cleared and the machine easily serviced.
It is a further object of the invention to provide directly in the blast head itself a compact and efficient means of separating debris and foreign material from the returning abrasive prior to its reuse.
It is yet another object of the present invention to provide an air wash separating device in a portable blast head for extracting debris and other contaminants from spent abrasive.
Other objects and advantages of the invention will be apparent from the concluding portion of the specification.